1. Field of the Invention
This invention generally relates to a heat insulator for a disc brake assembly. More specifically, the present invention relates to a heat insulator disposed between a piston and a friction member that reduces the heat transferred from the friction member to the hydraulic fluid of the disc brake assembly.
2. Background Information
Bicycling is becoming an increasingly popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving their components. One particular component of the bicycle, which has been extensively redesigned over the past years, is the braking systems of bicycles. In particular, the braking power of the braking systems is constantly being increased.
There are several types of bicycle brake devices, which are currently available on the market. Examples of some types of common bicycle brake devices include rim brakes, caliper brakes and disc brakes. If a rider wants a very high performance brake system, then the rider typically wants a disc brake system. Disc brake systems provide a substantial braking power in relationship to the amount of braking force applied to the brake lever. Moreover, disc brake systems typically provide a high level of consistency in all types of weather and riding conditions. Of course, riders constantly desire better performance from disc braking systems, i.e., disc brake systems that have more braking power.
Conventionally, a disc brake is composed of a caliper housing with one or more pistons and a pair of brake pads with one or both of the brake pads being movably mounted to the caliper housing. The brake pads are pressed against a disc or rotor that is fixed to the wheel to halt the rotation of the disc and thus the wheel. The brake pads are moved toward the disc either hydraulically or mechanically such as by a cam mechanism. The hydraulic disc brake systems typically provide a high level of consistency in all types of weather and riding conditions. However, one problem with hydraulically actuated disc brakes is that the hydraulic or actuating fluid can become overheated such that vapor-lock occurs. In other words, the heat generated by braking results in the hydraulic fluid increasing in volume so as to cause the brake pads to engage the brake disc even when the brake lever is in the release position. When vapor-lock occurs, the bicycle wheels can lock up and throw the rider off of the bicycle.
In the prior art disc brake systems, several methods have been utilized to avoid vapor-lock. For example, the caliper housing can be made larger to absorb more heat. Another method has been to make a larger brake disc with a wider surface area. Also, vapor-lock can be suppressed by utilizing high quality hydraulic fluid. Yet another (method to avoid vapor-lock has been to use brake or friction pads which do not transfer the heat to the brake housing as readily as conventional friction pads. Still another method to avoid vapor-lock is to utilize a heat insulator between the piston and the friction pads. These prior art methods of avoiding vapor-lock have many problems. One particular problem is that some of these solutions often are expensive to manufacture. Also, some of these prior art solutions are not completely effective.
In view of the above, there exists a need for a heat insulator for a disc brake assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
One object of the present invention is to provide a heat insulator that dissipates heat transferred from a friction member to the actuating fluid of a disc brake assembly.
Another object of the present invention is to provide a heat insulator that is versatile and can be used with existing disc brake assemblies to dissipate heat transferred to the actuating fluid.
Still another object of the present invention is to provide a heat insulator that is relatively simple and inexpensive to manufacture.
The foregoing objects can basically be achieved by providing a disc brake assembly with a heat insulator. The disc brake assembly includes a caliper housing, a first and a second friction member coupled to the caliper housing, a piston and the heat insulator. The first and second friction members form a rotor receiving slot between the first and second friction members. At least the first friction member is movably coupled to the caliper housing. The piston is movably coupled to the caliper housing to move the first friction member between a release position and a braking position. The piston has an internal recess. The heat insulator is disposed between the piston and the first friction member. The heat insulator has a first end with a first end surface received in the recess of the piston, a second end with a second end surface spaced from the first end surface and a side wall extending between the first and second end surfaces. The second end is partially received in the recess of the piston and the side wall has a protrusion extending therefrom to space the heat insulator from the piston.
The foregoing objects can also basically be achieved by providing a disc brake assembly with a modified heat insulator. The disc brake assembly includes a caliper housing, a first and a second friction member coupled to the caliper housing, a piston and the heat insulator. The first and second friction members form a rotor receiving slot between the first and second friction members. At least the first friction member is movably coupled to the caliper housing. The piston is movably coupled to the caliper housing to move the first friction member between a release position and a braking position. The piston has an internal recess. The heat insulator is disposed between the piston and the first friction member. The heat insulator has a first end with a first end surface received in the recess of the piston, a second end with a second end surface spaced from the first end surface and a side wall extending between the first and second end surfaces. The second end is partially received in the recess of the piston and the second end surface has a groove formed therein.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.